Well there should be a few new selectors quite soon actually. The transcripts collection proposal for example will need one, and I’m planning on adding some for experimenting with Parchment.
It would make sense to add selectors for existing extensions (it would also be good to have a list of them in one place!) I’ll go looking for the Zoom ones you mentioned, but I’m unaware of any others. If you know of more, please do share them.
Hmm, ok, so it looks like Zoom adds EXT:128-132. It also has @sound_data, an opcode removed from the final 1.1 spec, though it looks like a nop. I’ll change the range referred to in the private use area so that there’s no possibility of conflicts. And if we assign selectors for the Zoom opcodes then other interpreters could add them too, which might be good.